It is well established that malodour may be caused by a number of compounds including Volatile Surphuric compounds (VSC), nitrogen containing compounds and short fatty acids.
A source of nitrogen containing compounds, such as ammonia, is urine, faeces and blood giving a bad smell known by most people from either soiled diapers or other hygiene products, such as adult incontinence products, training pants, feminine napkins, tampons and the like.
The bad smell coming from diapers and the like is at least partly a consequence of growth of bacteria, especially Escherichia coli, Enterococcus spp. and Proteus spp. present on the skin in the perineum (the region between the anus and the external sexual organs). All strains of Proteus spp. form the enzyme urease during their metabolism. Urease has the ability to rapidly break down urea (constituting about 2% of human urine) into ammonia causing an unpleasant odour.
Removal or Reduction of Malodour in Hygiene Products
A number of odour controlling agent and systems have been described in the literature. For instance, carbon is e.g. in the form of activated carbon well-known for its ability to adsorb odoriferous molecules.
U.S. Pat. No. 5,593,398 discloses protective underwear with malodorous flatus filter comprising activated carbon as the malodour controlling agent.
Zeolitic materials have been shown to be effective against malodour associated with body fluids.
JP patent application no. 02068117 relates to deodorising means e.g. for diapers containing zeolite, copper and activated charcoal.
U.S. Pat. No. 3,903,259 concerns a method of deodorising diapers and human excreta comprising applying to the diapers or the excreta a chemical composition which in its simplest form consists of an acidic material, an antibiotic material, and a solvent. The impregnating composition may also contain a chelating agent and a wetting agent. The treatment of diapers results in a marked decrease in offensive odours from excreta, thus making the changing of sorted diapers less unpleasant.
U.S. Pat. No. 3,935,862 discloses a disposable diaper comprising means for inhibiting ammonia formation therein including an aminopolycarboxylic acid compound in an amount of at least 0.001 g per square inch.
U.S. Pat. No. 4,385,632 concerns a germicidal absorbent body for collecting blood, faeces and urine which contains a water-soluble copper salt which impedes bacterial growth, prevents the breaking down of urea into ammonia and complex-binds ammonia so as to prevent the occurrence of unpleasant odour.